In a sneak peek for the upcoming episode of MTV's "Teen Mom 2," Leah Messer says another tearful goodbye to her three daughters as she leaves for rehab again, after rushing home the first time on a threat that she would lose custody of her twins to her first ex-husband, Corey Simms.

"No don't leave!" Messer's daughter, Aleeah Grace (Gracie) shouts as she runs to her mother with open arms. Messer hugs and kisses her daughter on the head before picking her up and sitting her down on the couch next to her twin sister Ali and little sister Addy (whom Messer shares with her second ex-husband, Jeremy Calvert).

In a previous episode, Messer admitted that she needed help after Calvert served her with divorce papers. She decided to take steps to become a better person and a better mom by seeking treatment at an out-of-state rehab facility for depression and anxiety, as previously reported by HNGN.

But when Messer's mother Dawn dropped the twins off with Simms, he made statements that made Dawn worry. She called her daughter and warned her that Simms might try to file for abandonment and gain temporary full custody of the twins while Messer was away. She flew back on the next flight to secure custody of her daughters.

After her lawyer reached an agreement with Simms' lawyer, Messer made plans to return to rehab because it's the best decision for her and her kids.

"Gracie, mommy promises to call you as soon as I get there," Messer tells her daughters before she leaves again. "I love you, mommy will be back okay? I love you."

Watch the sneak peek below and be sure to catch the new episode of MTV's "Teen Mom 2," airing Thursdays at 10 p.m. ET on MTV.